| Abbreviation | Definition |
|---|---|
| ACTS | Automated Coin Toll System |
| ACVS | Ameritech Customized Video Service |
| ADAD | Automatic Dialing Announcing Device |
| ADAS | Automated Directory Assistance System |
| ADC | Access Deficit Charge |
| ADC | Analog-to-Digital Converter |
| ADC | Applied Digital Communications |
| ADCCP | Advanced Data Communications Control Procedures |
| ADF | Application Dedicated File |
| ADIF | Accounting Data Interchange Format |
| ADIT | Alien Documentation Identification Telecommunications |
| ADLI | Automatic Dial Line Identification |
| ADM | Add/Drop Multiplexer |
| ADM3X | DS3 Add-Drop Multiplex |
| ADN | Abbreviated Dialing Number |
| ADN | Advanced Digital Network |
| ADPT | Automated Data Processing Telecommunications |
| ADSRF | Additional Device Savings Recovery Fee |
| ADTM | Asynchronous Data Transfer Mode |
| ADTN | Administrative Data Telecommunications Network |